The long-term objective of the proposed activity is to develop, and market an anatomically compatible chronic VAS based on a direct motor driven axial flow blood pump. The specific aim of the Phase I research is to demonstrate the mechanical integrity and blood seal performance together with satisfactory hydraulic and hemolysis performance of the device. The Phase II in vitro and in vivo testing is designed to demonstrate endurance capability, hemolysis, performance and antithrombogenic characteristics through in vitro endurance and chronic in vivo testing. Protocols for Phase I will model those previously developed for the axial flow peripherally introduced Hemopump, which is currently undergoing clinical trials. The technical innovation involves a chronic VAS with a 25cc implantable volume based on demonstrated axial flow blood pumping technology. Other elements of the VAS; the motor, motor controls, percutaneous access and the support pack have a strong technology base in chronic NHLBI VAS research. The commercial potential is based on the small implant volume and lower cost of the VAS compared to conventional cyclic delivery devices.